1. Field of the Invention
The present invention relates to internal combustion engines, and more specifically to air-cooled internal combustion engines having hydraulically-operated cooling fans, these engines including hydraulic lines for conveying fluid to the cooling fans in which are located flow control valves.
2. The Prior Art
Air-cooled internal combustion engines which are cooled by hydraulically-operated cooling fans that are operated by the passage of fluids through their hydraulic couplings are well known. In many engines of this type the cooling fan will be operated by the flow of engine lubricating oil therethrough, and these engines will include hydraulic lines for circulating the engine lubricating oil pumped from the oil pan to the hydraulic coupling of the cooling fan. Such hydraulic lines will have valves therein to control the flow of the lubricating oil therethrough and thus determine the speed of rotation of the cooling fans. The operation of these valves will often be controlled by an elastic temperature gauge which will be positioned to detect the temperature of a structural part of the engine, or else by a temperature gauge which will be positioned to detect the temperature of the engine exhaust gas.
Such prior art engines have not been known to utilize more than two temperature gauges to control the operation of the value in the hydraulic line.
Tests by the present inventors have shown, however, that both the fuel consumption of the engine and the sound emissions therefrom can be reduced if the rotational speed of the cooling fan can be continuously optimized with respect to not only the temperature of a structural part of the engine and the temperature of the engine exhaust gas, but if the cooling fan's rotational rate can take into consideration the temperature of the lubricating oil, the air temperature of the surrounding atmosphere and the air pressure of the surrounding atmosphere, i.e., since all of these parameters have been found to affect the operation of the engine.
It is thus an object of the present invention to provide a regulation apparatus which can control the flow of fluid to a hydraulically-operated cooling fan in an air-cooled internal combustion engine based on the relevant parameters which have been found to affect its operational characteristics.